She said HCG tricks your brain into thinking you body is pregnant. McCarthy said science has shown her HCG helps the body metabolize faster.

"This will help you have patience to learn how to change your ways and change your relationship with food," said McCarthy.

But the program requires more than injections. It comes with a very restrictive low-calorie diet. And there are plenty of skeptics.

"The HCG doesn't have anything to do with the weight loss," said Dr. Barry Ramos, a cardiologist. "The fact is if you go on a 500 calorie-a-day diet, you lose weight. The bottom line is, it's potentially dangerous because you don't know what you're injecting in your body. The best way to lose weight is diet and exercise," he said.

But believers said the diet works wonders. Even if the HCG is just a placebo, as some claim, Paloni said the proof is in her new body.

"It's an amazing thing. It really is. When I took a shot I was never hungry. I'm not hungry. I've learned how to eat better. I feel great and I truly believe that I will not put the weight back on," she said.

There are many HCG products available online. But there are also dozens of studies and blogs that say it doesn't work. The program costs between $300 and $565 for six weeks.